“The God of Genesis not only sorted out night and day. He invented the week, a seven-day cycle without any astronomical significance, our only temporal unit that bears no relationship to the arrangement or operation of the sun, the earth, our moon, or any other heavenly sphere. God made it up.”
Michael Downing, Spring Forward: The Annual Madness of Daylight Savings Time
If God made up the week, then in my never-to-be-humble opinion, I think we can choose what day to call Sabbath. I have tried Mondays, Wednesdays, Fridays, Saturdays, and Sundays. I even flirted with a Tuesday, but it never took. I’ve never managed a Thursday.
Romans 14:4 says, “One man considers one day more sacred than another; another man considers every day alike. Each one should be fully convinced in his own mind.”
I’ve been fully convinced many times, in many ways. The important thing is that the week, this thing God made up, ends every seven days. As Veggie Tales says in Moe and the Big Exit, “Lay off the trail one day a week.”